The well-known picture puzzle, i.e., the jigsaw puzzle employing a large number of interlocking pieces has been well-known for a long period of time. Such puzzles reached the peak of their popularity in the United States during the 1930's and 40's, before the advent of television. Typically, these puzzles are created by beginning with a picture of a scene or an object or person and then cutting or stamping this single picture into a plurality of smaller interlocking pieces, whereby each of the individual pieces carries a small portion of the original scene. The pieces are constructed such that they will only fit together in one way and, by a process of deduction and trial and error, the original composite scene is then reconstructed from the individual pieces. This type of jigsaw puzzle may be as complex or as simple as desired, depending upon the number of pieces and the original picture to be reconstructed.
At the present time it appears that the conventional multi-piece jigsaw puzzle has been developed to its greatest extent and that no further improvements may be made in order to make the puzzle more complex. The more advanced picture puzzles may have a circular border, thereby eliminating the initial advantage of constructing the four corners of the puzzle. Also, some puzzles may have large areas of the same color or have a small pattern such that it becomes very difficult to determine the exact location of many of the pieces.
A branch of the physical sciences which is very far removed from the entertainment aspects of jigsaw puzzles has been undergoing increased development since it was first disclosed in 1947. This concept is holography, whereby three-dimensional images appear in space when viewed through a two-dimensional sheet of film. The technology surrounding holography has been steadily increasing since its discovery in 1947, and the discovery of the laser in 1960 has contributed greatly to the advance of holography.
Although the initial holograms were formed by the use of quasi-coherent light produced by a mercury arc lamp, currently the most popular technique for forming holograms uses coherent light. As the development of the laser was advanced, they became the ideal source for use with holograms, since lasers are a ready source of coherent light. However, the science of holography has advanced to the state where it has now been demonstrated that laser produced holograms may be illuminated for viewing solely by ordinary, incoherent light which is termed white light and, in this regard, see the article in the October, 1976 issue of "Scientific American" by E. N. Leith.